1. Field of the Invention
The subject invention generally pertains to the prevention of a vehicle from overturning and more specifically to an outrigger for a vehicle.
2. Description of Related Art
Outriggers are often used to stabilize or prevent a parked vehicle from tilting. They are commonly found on service or construction vehicles that become generally top-heavy due to a crane mast or an extension ladder extending from the vehicle. When the vehicle parks to perform its service operation, the outrigger is extended sideways from the stationary vehicle and downward against the ground to widen the vehicle""s base. When the service operation is complete, the outrigger is returned to a stored position, so as not to impede the vehicle""s travel. Outriggers are usually moved manually or hydraulically between their stored and extended positions. Although such outriggers work well for parked vehicles, they are ineffective in preventing traveling vehicles from overturning.
Traveling vehicles can be caused to tip over for several reasons. For example, if the wheels on only the right or left side of the vehicle drive over an obstacle or void in the road or driving surface, that disruption could overturn the vehicle. An inclined driving surface would have a similar tipping effect upon a vehicle traversing the incline. Quick turns can also create a centrifugal force sufficient to overturn a vehicle. In the case of a forklift truck, raising a heavy load high overhead can make the forklift top-heavy and prone to tipping. To prevent a moving vehicle from tipping over, some vehicles include a ballast that moves automatically to shift the vehicle""s center of gravity to counterbalance the tipping. Various types of moveable ballasts are disclosed in U. S. Pat. Nos. 2,916,172; 3,497,095; 4,221,530; and 4,502,709. Unfortunately, the weight of a moveable ballast has to be significant in comparison to the weight of the vehicle to be really effective. And a ballast of substantial weight can add unnecessary bulk and cost to a vehicle.
Minimizing bulk is especially important for vehicles, such as forklift trucks that need to maneuver within narrow aisles and between various obstacles that typically clutter shipping and receiving areas of a building. Shopping carts are another example of a vehicle that needs to travel within narrow aisles, and they tend to be top heavy and prone to tipping, especially when a child is in the cart. Lawn tractors often need to maneuver among trees and other obstacles, and are more prone to tipping when traversing inclined terrain. These are just a few examples of vehicles that could benefit from a compact anti-tipping device.
In order to provide a traveling vehicle with protection against overturning without adding unnecessary weight or bulk to the vehicle, an outrigger is provided that includes an engaging member that normally stays in a retracted, stored position, but then automatically extends to brace the vehicle in response to the vehicle tipping to a predetermined limit.
In some embodiments, a inclination sensor and a latch are combined into a single element that normally holds a spring-loaded arm in its retracted, stored position and then automatically releases the arm upon sensing the vehicle tipping to the predetermined limit.
In some embodiments a spring-loaded arm of an outrigger is unlatched by a solenoid actuator in response to an inclination responsive switch, such as a mercury switch.
Some embodiments include a mechanical inclination sensor that detects a vehicle tilting to a predetermined limit by contacting the surface upon which the vehicle is traveling.
In some embodiments, an outrigger comprises an inflatable bladder.